spaghetti
Active Member
Hi there, I've just finished refurbishing a Sony TA-4650 VFET amp. First thing I did was remove the VFETs, they all tested fine on the DMM, so I went on replacing the suicide diodes, making the PSU voltage modification in order to center the B+/B- values, and replacing four 1.5K ohm resistors with 3.3K as per service bulletin.
Right now the VFETs are still outside of the amp, I am a little nervous about putting them back and I would like some reassurance that everything looks fine.
These are the voltages at the VFETs sockets:
Q312 2SK60
Q361 2SJ18
All drains are 0V. The G-S voltage difference is always about 14V, I think it can be modified by setting RT301 and RT351, and I will have to adjust those trimmers later in order to set the bias correctly.
Can anyone confirm me it's ok to put the VFETs back into the amp and power it on?
Thanks
Right now the VFETs are still outside of the amp, I am a little nervous about putting them back and I would like some reassurance that everything looks fine.
These are the voltages at the VFETs sockets:
Q312 2SK60
G -60V
S -44V
Q311 2SJ18S -44V
G 60V
S 44V
S 44V
Q361 2SJ18
G 58V
S 44V
Q362 2SK60S 44V
G -58V
S -44V
S -44V
All drains are 0V. The G-S voltage difference is always about 14V, I think it can be modified by setting RT301 and RT351, and I will have to adjust those trimmers later in order to set the bias correctly.
Can anyone confirm me it's ok to put the VFETs back into the amp and power it on?
Thanks
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